// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_PATH_SERVICE_H_
#define BASE_PATH_SERVICE_H_

#include <string>

#include "base/base_export.h"
#include "base/base_paths.h"
#include "base/gtest_prod_util.h"
#include "build/build_config.h"

namespace base {

class FilePath;
class ScopedPathOverride;

// The path service is a global table mapping keys to file system paths.  It is
// OK to use this service from multiple threads.
//
class BASE_EXPORT PathService {
public:
    // Retrieves a path to a special directory or file and places it into the
    // string pointed to by 'path'. If you ask for a directory it is guaranteed
    // to NOT have a path separator at the end. For example, "c:\windows\temp"
    // Directories are also guaranteed to exist when this function succeeds.
    //
    // Returns true if the directory or file was successfully retrieved. On
    // failure, 'path' will not be changed.
    static bool Get(int key, FilePath* path);

    // Overrides the path to a special directory or file.  This cannot be used to
    // change the value of DIR_CURRENT, but that should be obvious.  Also, if the
    // path specifies a directory that does not exist, the directory will be
    // created by this method.  This method returns true if successful.
    //
    // If the given path is relative, then it will be resolved against
    // DIR_CURRENT.
    //
    // WARNING: Consumers of PathService::Get may expect paths to be constant
    // over the lifetime of the app, so this method should be used with caution.
    //
    // Unit tests generally should use ScopedPathOverride instead. Overrides from
    // one test should not carry over to another.
    static bool Override(int key, const FilePath& path);

    // This function does the same as PathService::Override but it takes extra
    // parameters:
    // - |is_absolute| indicates that |path| has already been expanded into an
    // absolute path, otherwise MakeAbsoluteFilePath() will be used. This is
    // useful to override paths that may not exist yet, since MakeAbsoluteFilePath
    // fails for those. Note that MakeAbsoluteFilePath also expands symbolic
    // links, even if path.IsAbsolute() is already true.
    // - |create| guides whether the directory to be overriden must
    // be created in case it doesn't exist already.
    static bool OverrideAndCreateIfNeeded(int key,
        const FilePath& path,
        bool is_absolute,
        bool create);

    // To extend the set of supported keys, you can register a path provider,
    // which is just a function mirroring PathService::Get.  The ProviderFunc
    // returns false if it cannot provide a non-empty path for the given key.
    // Otherwise, true is returned.
    //
    // WARNING: This function could be called on any thread from which the
    // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.
    //
    typedef bool (*ProviderFunc)(int, FilePath*);

    // Call to register a path provider.  You must specify the range "[key_start,
    // key_end)" of supported path keys.
    static void RegisterProvider(ProviderFunc provider,
        int key_start,
        int key_end);

    // Disable internal cache.
    static void DisableCache();

private:
    friend class ScopedPathOverride;
    FRIEND_TEST_ALL_PREFIXES(PathServiceTest, RemoveOverride);

    // Removes an override for a special directory or file. Returns true if there
    // was an override to remove or false if none was present.
    // NOTE: This function is intended to be used by tests only!
    static bool RemoveOverride(int key);
};

} // namespace base

// TODO(brettw) Convert all callers to using the base namespace and remove this.
using base::PathService;

#endif // BASE_PATH_SERVICE_H_
